Method and Apparatus Reporting Channel Quality Indicator of Communication System

ABSTRACT

The present invention provides a method and apparatus reporting a channel quality indicator (CQI) of a communication system, including: detecting a first measurement reflecting a first communication quality of the communication system, providing first reference(s) respectively corresponding to indicator level(s), providing CQI according to the indicator level(s) and a relation between the first measurement and the first reference(s), and updating one (or more) first reference according to a second measurement reflecting a second communication quality of the communication system. For example, the first measurement can represent signal to interference ratio or mutual information, and the second measurement can represent data error rate or throughput. First reference(s) can be further adjusted according to a third measurement, e.g., a power scheduling of base station, such that CQI can be updated if base station schedules additional transmission power.

The is a continuation-in-part application of U.S. patent applicationSer. No. 13/113,328, filed May 23, 2011, the contents of which areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to method and apparatus reporting channelquality indicator of communication system, and more particularly, tomethod and apparatus dynamically adapting a relation which associates achannel measurement with the channel quality indicator.

BACKGROUND OF THE INVENTION

Communication systems, especially wireless communication systems, havebecome an important portion of modern society. Generally speaking, in awireless communication system, a base station (e.g., NodeB) establishesradio coverage over a cell, and a terminal (e.g., UE, user equipment)can therefore communicates with the base station by signal transmissionthrough a wireless communication channel between the base station andthe terminal. By different communication parameter combinations such ascombinations of different modulation schemes and/or coding schemes, thecommunication channel, involving medium and environment where wirelesssignals transmit, can be separated to a plurality of physical channelsfor multiple-access. Some of the physical channels implement downlinkchannels for transmission from the base station to the terminal; othersare allocated as uplink channels for transmission from the terminal tothe base station. From another aspect, some of the physical channels areused for data transmission, and others are used for transmission ofcontrol information which is used for initiating, managing, handoverand/or ending of the communication channel.

As a wireless communication system becomes more popular, the demand ofhigher throughput becomes more important. To fulfill throughput demand,the base station needs to provide the data service in an efficient wayto accommodate various applications, e.g. voice service, data download,streaming, gaming, browsing, and etc, under the limited channelbandwidth. An efficient way to maximize the cell capacity is to allocatehigher data rate to terminals with better channel qualities. In modernwireless communication systems, this concept is realized by adaptivemodulation and coding scheme (adaptive MCS). The terminal shall monitorthe downlink channel quality and report the quality metric, oftenreferred to as channel quality indicator (CQI), to the base station.Then the base station can schedule proper data transmission for theterminals to fit channel capacity of each terminal, and maximize thecell capacity by adjusting the coding rate of channel decoder to controlthe capability of error protection, and by selecting the suitablemodulation scheme to achieve the spectral efficiency.

For example, in communication systems following the third generation(3G) wideband code division multiple access (WCDMA) standard, the CQIreporting is a mandatory feature in the evolution version of thestandard, which is named as high speed packet access (HSPA), for theprocedure of high-speed downlink shared channel (HS-DSCH) reception. Inresponse to CQI reporting of a terminal, the base station reportsinformation about a transport format resource combination (TFRC) to theterminal; with TFRC, the terminal can reliably receive data from thebase station under the experienced or to-be-experienced channelconditions. The TFRC means a communication parameter combinationallocating the physical channel resources, including modulation andnumber of physical channels, and the size of transport block transmittedin the downlink data channel(s). The terminal shall determine thesupportable TFRC as the CQI reporting value, and this reporting must beindependent of channel variations due to, e.g., the Doppler shift, delayspread and so on. In other words, same values of CQI reporting mean sameblock error rate (BLER) or same throughput that can be achieved if thebase station follows CQI reporting of the terminal.

As a terminal equips a receiver which includes an inner receiver and anouter receiver (a channel decoder), a common quality metric (e.g., SIR,Signal to Interference Ratio or MI, mutual information) reflecting aquality of the communication channel is estimated after the innerreceiver and before the outer receiver; however, this kind of qualitymetric cannot directly reflect the BLER quality and throughput.Moreover, the quality metric measurement depends on pilot part in onephysical channel, not the data part in another physical channel;therefore it leads to differences under different channel variations.That is, a fixed mapping relation which directly maps the quality metricto CQI does not generate proper CQI reporting against channelvariations.

SUMMARY OF THE INVENTION

Therefore, the present invention adapts the mapping relation betweenmeasured channel quality and CQI to generate a universal qualityreporting value that reflects BLER and/or throughput directly.

An example of the invention provides a method reporting a channelquality indicator CQI of a communication system; the method can beapplied to a terminal of the communication system, and includes:detecting a first measurement reflecting a first communication quality(e.g., SIR or MI) of the communication system; providing a series of aplurality thresholds (TH(i−1), TH(i) and TH(i+1), etc.) and a pluralityof mapping functions (g(i,.) and g(i+1,.), etc); the plurality ofthresholds corresponding to a plurality of bins (B(i) and B(i+1), etc)with each bin B(i) defined by two adjacent thresholds TH(i−1) and TH(i);each mapping function g(i,.) in association with a bin B(i); wherein thefirst measurement X (e.g., SIR or MI) is matched into one of the bins,such as a bin B(i_m), and the mapping function g(i_m,.) in associationwith the matched bin B(i_m) maps the first measurement X to the channelquality indicator CQI by CQI=g(i_m,X); and updating at least one of theplurality of thresholds according to a second measurement, e.g., BLERreflecting a second communication quality (e.g., a block error ratewhich represents CRC error rate of a transport block) of thecommunication system or the receiving throughput of the terminal.

In an embodiment, the communication system adopts one of a plurality ofcommunication parameter combinations for communication, thecommunication parameter combinations are categorized to a plurality ofcombination schemes MCS(i−1), MCS(i) and MCS(i+1), etc.; eachcombination schemes MCS(i) corresponds to two adjacent thresholdsTH(i−1) and TH(i) respectively as a bottom threshold and an upperthreshold.

One embodiment of the invention implements a target BLER criterion. Whenthe communication system adopts a communication parameter combinationwhich is categorized to an operating combination scheme MCS(i_op) withan operating bottom threshold TH(i_op−1), if the first measurement (SIRor MI) falls in a predetermined neighborhood of the operating bottomthreshold TH(i_op−1), update the operating bottom threshold TH(i_op−1)by lowering the operating bottom threshold TH(i_op−1) if the secondmeasurement BLER is lower than a target value, or by increasing theoperating bottom threshold TH(i_op−1) if the second measurement BLER ishigher than the target value.

One embodiment of the invention implements an optimum throughputcriterion, including: collecting a plurality of the second measurementsU(i−1), U(i), and U(i+1) etc., each second measurement U(i) being thethroughput corresponding to the combination schemes MCS(i); andcollecting a plurality of auxiliary measurements BLER(i−1), BLER(i) andBLER(i+1) etc., each auxiliary measurement being BLER(i) correspondingto the combination schemes MCS(i). When the communication system adoptsa communication parameter combination which is categorized to anoperating combination scheme MCS(i_op) with an operating bottomthreshold TH(i_op−1) and an operating upper threshold TH(i_op), if thefirst measurement (SIR or MI) falls in a predetermined neighborhood ofthe operating bottom threshold TH(i_op−1) and if a auxiliary measurementBLER(i_op−1) corresponding to a lower combination scheme MCS(i_op−1)falls out of two predetermined ranges, update the operating bottomthreshold TH(i_op−1) by lowering the operating bottom thresholdTH(i_op−1) if a second measurement U(i_op) corresponding to theoperating combination scheme MSC(i_op) is higher than a secondmeasurement U(i_op−1) corresponding to the lower combination schemeMCS(i_op−1), or by increasing the operating bottom threshold TH(i_op−1)if the second measurement U(i_op−1) is lower than the second measurementU(i_op).

The two predetermined ranges are respect proximities of a bottom boundand an upper bound of BLER. If the first measurement (SIR or MI) fallsin the predetermined neighborhood of the operating bottom thresholdTH(i_op−1) and if the auxiliary measurement BLER(i_op−1) falls in thepredetermined range of the upper bound, increase the operating bottomthreshold TH(i_op−1). If the first measurement (SIR or MI) falls in thepredetermined neighborhood of the operating bottom threshold TH(i_op−1)and if the auxiliary measurement BLER(i_op−1) corresponding to the loweroperating combination scheme falls in the predetermined range of thelower bound, update the operating bottom threshold TH(i_op−1) accordingto a comparison between a target value and the auxiliary measurementBLER(i_op).

Furthermore, if the first measurement (SIR or MI) falls in apredetermined neighborhood of the operating upper threshold TH(i_op) andif the auxiliary measurement BLER(i_op) falls out of the twopredetermined ranges, update the operating upper threshold TH(i_op) byincreasing the operating upper threshold TH(i_op) if the secondmeasurement U(i_op) is higher than a second measurement U(i_op+1)corresponding to a higher operating combination scheme MCS(i_op+1), orby lowering the operating upper threshold TH(i_op) if the secondmeasurement U(i_op) is lower than the second measurement U(i_op−1). Ifthe first measurement (SIR or MI) falls in the predeterminedneighborhood of the operating upper threshold TH(i_op) and if theauxiliary measurement BLER(i_op) falls in the predetermined range of theupper bound, increase the operating upper threshold TH(i_op).

An objective of the invention is providing a method reporting CQI of acommunication system, including: detecting a first measurement (e.g.,SIR or MI), providing first reference(s) (e.g., aforementioned thresholdTH(.)) respectively corresponding to predetermined indicator level(s)CQI(.), providing CQI according to the indicator level(s) and a relationbetween the first measurement and the first reference(s), and updatingone (or more) of the first reference according to a second measurement(e.g., BLER or throughput). For example, if the first measurement (SIRor MI) is greater than a first reference TH(i) and less than anotherfirst reference TH(i+1), then CQI can be set equal to the indicatorlevel CQI(i) which corresponds to the first reference TH(i).

In an embodiment where MI is adopted as the first measurement, themethod can further include: evaluating MI of the communication system bymapping SIR to MI through a SIR-to-MI mapping. For example, MI can be ameasurement to quantifying amount of information allowed to betransmitted under a given environment. While considering a communicationsystem utilizing QPSK to transmit symbols of 2 bits, value of MI willrange from 0 to 2 bits. A seriously degraded (noisy and interfered)communication environment causes MI close to 0, reflecting that barelyany information (bits) can be effectively transmitted between terminaland base station. On the other hand, a nearly perfect communicationenvironment facilitates MI close to 2, reflecting that the environmentcan support full transmission capacity. Because high SIR helps toincrease MI and low SIR leads to low MI, MI can be derived (calculated)from SIR.

In an embodiment, the method further includes: updating one (or more)first reference TH(.) according to a third measurement which reflectsinformation of a base station of the communication system, e.g., a powerscheduling information of the base station. For example, a firstreference TH(i) can be decreased if the third measurement reflects thatthe base station schedules an additional transmission power for thecombination scheme MCS(i) and the indicator level CQI(i) whichcorresponds to the first reference TH(i). As a terminal (UE) operates,it collects power scheduling information which reflects how a servingbase station schedules power for different indicator levels CQI(.). Byanalyzing power scheduling information, If the terminal finds that thebase station schedules additional power for a given indicator levelCQI(i), then the terminal can update the corresponding threshold TH(i)by lowering (decreasing) it. The threshold TH(i) can be offset by anamount which reflects the additional transmission power of the basestation known from the third measurement. For example, the offset amountcan be set greater if the additional transmission power is greater.

Consider evaluating CQI for a given first measurement X (e.g., SIR orMI) which is less than an original value THV1 of the threshold TH(i), sothe measurement X originally fails to match the level CQI(i); afterdecreasing the threshold TH(i) to a lower value THV0, the measurement Xcan now apply the level CQI(i) if the measurement X is greater than thevalue THV0. That is, if a difference between values THV1 and THV0 isgreater than a difference between the measurement X and the value THV0,then the additional transmission power of the base station can wellcompensate (increase) original insufficient SIR or MI, and thus theoriginally unachievable level CQI(i) can now be applied.

An objective of the invention is providing a method for reporting CQI bya transmitter of a communication system, including: detecting a firstmeasurement (e.g., SIR or MI), providing first reference(s) (e.g.,threshold TH(.)) corresponding to predetermined indicator level(s)CQI(i), evaluating CQI according to the levels CQI(i) and a relationbetween the first measurement and the level(s) CQI(i), and updatingfirst reference(s) according to a second measurement and a thirdmeasurement which respectively reflect a second communication quality ofthe communication system (e.g., BLER or throughput) and an informationof a base station of the communication system (e.g., power schedulinginformation of a base station of the communication system).

An objective of the invention is providing a method for reporting CQI,including: obtaining a measurement (e.g., power scheduling information),and updating CQI according to the measurement, such that CQI changesfrom a first indicator level (e.g., a lower level CQI(i−1)) to a secondindicator level (e.g., a higher level CQI(i)) when the measurementreflects that a base station of the communication system schedulesadditional transmission power for the second indicator level.

An objective of the invention is providing an apparatus for reportingCQI of a communication system, including an estimation unit forproviding a measurement, and a module (e.g., a mapping module) forupdating the channel quality indicator according to the measurement,such that the channel quality indicator changes from a first indicatorlevel to a second indicator level when the measurement reflects that abase station of the communication system schedules additionaltransmission power for the second indicator level.

Numerous objects, features and advantages of the present invention willbe readily apparent upon a reading of the following detailed descriptionof embodiments of the present invention when taken in conjunction withthe accompanying drawings. However, the drawings employed herein are forthe purpose of descriptions and should not be regarded as limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects and advantages of the present invention will becomemore readily apparent to those ordinarily skilled in the art afterreviewing the following detailed description and accompanying drawings,in which:

FIG. 1 illustrates a communication system according to an embodiment ofthe invention;

FIG. 2 and FIG. 11 illustrate adaptation of SIR (or MI) to CQI mappingrelation according to embodiments of the invention;

FIG. 3 illustrates a threshold decision criterion according to anembodiment of the invention;

FIG. 4 illustrates threshold updating based on the criterion of FIG. 3according to an embodiment of the invention;

FIG. 5 illustrates a flow implementing the threshold decision of FIG. 3according to an embodiment of the invention;

FIG. 6 illustrates a threshold decision criterion according to anotherembodiment of the invention;

FIG. 7 and FIG. 8 illustrate threshold updating based the thresholddecision of FIG. 6 according to an embodiment of the invention;

FIG. 9 and FIG. 10 illustrate flows implementing the threshold decisionof FIG. 6 according to an embodiment of the invention; and

FIG. 12 illustrates a flow according to an embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Please refer to FIG. 1 illustrating a terminal 14 communicating to abase station 12 in a communication system 10, e.g., a 3G (or 4G)wireless mobile communication system. The invention can be applied tothe terminal 14, which includes an inner receiver 16, an outer receiver18, a first estimation unit 20, a mapping module 22, a second estimationunit 24 and an adaptation module 26.

For downlink communication, data to be transmitted to the terminal 14are arranged into data blocks (transport blocks) in the base station 12,and the base station 12 transmits to the terminal 14 with data blockscarried in the high speed downlink shared channel (HS-DSCH) and withcontrol information carried in the high-speed shared control channel(HS-SCCHs), including TFRC. The terminal 14 decodes the data and controlinformation by the inner receiver 16 and the outer receiver 18. Theinner receiver 16 behaves like an inverse function of the fading channeleffect, or called the equalization, to get the estimation of transmittedsymbols from the base station 12. These symbols are further decoded andtransformed into the information bits by the outer receiver 18. Theinner receiver 16 performs the functionalities of filtering, frequencyand timing synchronization, removal of channel effects, etc. The outerreceiver 18 executes the operation of physical channel and constellationde-mapping, de-interleaving, de-rate-matching, HARQ combining, channeldecoding, bit descrambling, and CRC (Cycle Redundancy Check)de-attachment, etc. According to signals received by the inner receiver16, the estimation unit 20 provides SIR, MI and/or information of basestation. SIR reflects a signal to interference quality of thecommunication channel. MI reflects mutual information betweentransmitted signal and received signal of the communication systemincluding the base station 12 and the terminal 14, e.g., quantifiesamount of information can be carried by the communication environment.For example, MI can be expressed by I(X; R|H)=H(X|H)−H(X|R, H), wherethe terms X, R and H respectively represent transmit signal, receivedsignal and channel response. In an embodiment, MI can be derived(calculated) from SIR; or, MI can be directly calculated withoutdetecting SIR. The information of base station, e.g., power schedulinginformation for the terminal 14, reflects how the serving base station12 schedules power for different indicator levels CQI(.).

For CQI reporting, a common way is to determine the received quality byestimating SIR. For example, in the 3GPP technical specification 25.214,a CQI mapping table defines 30 levels (CQI(1) to CQI(30)); theirrequired SIRs for supporting a BLER of 0.1 are monotonically increasingby a step of 1 dB SIR differences in the static channel condition. Amongthe CQI(1) to CQI(30), CQI(1) and CQI(30) respectively represent theTFRC with the lowest and highest required channel quality for reliablereception with BLER=0.1. Hence, the mapping of reported CQI and SIR isalso a linear relation under a static channel. However, when thecommunication channel from the base station 12 to the terminal 14 actslike a fading channel instead of a static channel, the linear relationis no longer valid, and proper CQI reporting can not be accomplished.

Please refer to FIG. 2 which illustrates SIR (or MI) to CQI mappingrelation according to an embodiment of the invention. The SIR (or MI) toCQI mapping relation works with a plurality of thresholds (orreferences) TH(i−2), TH(i−1), TH(i), TH(i+1), TH(i+2) etc, and aplurality of piecewise mapping functions such as g(i−1,.) and g(i,).Every two adjacent thresholds form a bin, such as the bin B(i) has anupper threshold TH(i) and a bottom threshold TH(i−1), and the bin B(i−1)has thresholds TH(i−2) and TH(i−1) as its bottom and upper thresholds,respectively. Each of the bin corresponds to a mapping function; forexample, the bin B(i) corresponds to the mapping function g(i,.), andthe bin(i−1) is in association with the mapping function g(i−1,.). Whilemapping a measurement (e.g., SIR or MI) value x to a corresponding CQI,the value x is first matched to a bin. For example, if the value x isless than the threshold TH(i) but greater than the threshold TH(i−1), itis matched to the bin B(i); and therefore the mapping function g(i,.)which corresponds to the bin B(i) is used to map the value x to a mappedCQI value y by y=g(i,x). The CQI value y can be further quantized to oneof the CQI(1) to CQI(30) if necessary. In an embodiment, each of themapping function g(i,.) is a linear function defined over thresholdsTH(i−1) to TH(i), e.g.,g(i,x)=CQI(i−1)+(x−TH(i−1))*(CQI(i)−CQI(i−1))/(TH(i)−TH(i−1)) withCQI(i−1) and CQI(i) being two predetermined levels. Or, in a simplifiedembodiment as shown in FIG. 11, the mapping function g(i,.) candegenerate to a uniform level CQI(i−1); that is, if the value x isbetween the thresholds TH(i−1) and TH(i), then CQI can be set equal tothe level CQI(i−1).

As previously discussed, communication channel has its owncharacteristics dependent on many factors, such as propagation delayspread, Doppler and/or multiple-path fading. There is a mutualcorrelation between SIR (or MI), BLER, throughput supported by thechannel, channel characteristics, and communication parametercombination adopted to establish the channel. For example, with given(fixed) BLER and channel characteristics, a communication parametercombination delivering higher throughput needs higher SIR (or MI). Withgiven BLER and throughput, a fading channel demands better SIR (or MI)than a static channel.

As the channel characteristics vary, a fixed SIR (or MI) to CQI mappingrelation cannot reflect the mutual correlation. To address the issue,the invention provides an adaptation technique for updating the SIR (orMI) to CQI mapping according to channel characteristics. As shown inFIG. 2, the adaptation is achieved by adjustment of the thresholds. Inan embodiment, each of the thresholds can be individually updated withdistinct adjustment.

With adjusted thresholds, bins and corresponding mapping functions workdifferently to meet nature of channel characteristics. For example, thevalue x originally matched to the bin B(i) now falls in the bin B(i−1)between the updated threshold TH(i−2) and TH(i−1), and it will be mappedto a new lowered CQI level by the mapping function g(i−1,.). Thethreshold TH(i) for a fading channel can be greater than that for astatic channel; it reflects the correlation: with given SIR or MI, thefading channel suffers from lower throughput of lower CQI; orequivalently, if the fading channel and the static channel adopt thesame CQI (and therefore the same throughput), the fading channel demandsbetter SIR (or MI) than the static channel.

In two embodiments of the invention, two criterions are provided toupdate the thresholds. Please refer to FIG. 3 which illustrates athreshold decision according to one embodiment of the invention. For agiven communication parameter combination and a given channelcharacteristics, BLER increases as SIR (or MI) decreases. Thiscorrelative relation is illustrated by two curves cv(i) and cv(i+1)respectively corresponding to two different communication parametercombinations. The two communication parameter combinations arerespectively categorized to combination schemes MCS(i) and NCS(i+1),each combination scheme generally refers to a collection ofcommunication parameter combinations which have similar SIR(orMI)/BLER/throughput performances. For example, the combination schemeMCS(i) associated with the curve cv(i−1) can correspond to a lower CQI,so the combination scheme MCS(i) delivers lower throughput but gainsbetter (lower) BLER with a given SIR or MI.

The curves of different MCSs can be used to decide the thresholds ofFIG. 2. By setting a target value target_BLER for BLER performance,intersection of the target_BLER and each curve cv(i) can be used todefine corresponding threshold TH(i−1). That is, the threshold TH(i−1)acts as a bottom threshold for combination scheme MCS(i) to reflectwhether the combination scheme MCS(i) can properly work under a givenSIR (or MI); if SIR (or MI) of the communication channel is lower thanthe threshold TH(i−1), the combination scheme MCS(i) suffers BLER higherthan the target value target_BLER, and therefore the CQI correspondingto the combination scheme MCS(i) is not preferred; instead, the mappingfunction defined between thresholds TH(i−1) and TH(i−2) can be appliedto decide a suitable (lower) CQI for the given SIR (or MI).

Different channel characteristics lead to different curve cv(i) anddifferent threshold TH(i−1). To approach the ideal bottom thresholdTH(i−1) at intersection of the curve cv(i) and the target valuetarget_BLER, measured SIR (or MI) and measured BLER are referred totrack actual behavior of the curve cv(i). Following discussion of FIG.3, please refer to FIG. 4 illustrating threshold updating according toan embodiment of the invention. When the terminal 14 is working with agiven combination scheme MCS(i_op) (an operating combination scheme), ameasured SIR or MI and a measured BLER are used for adjustment of thecorresponding bottom threshold TH(i_op−1). To update a current thresholdTH(i_op−1) toward the ideal threshold TH(i_op−1), a neighborhood aroundthe current threshold TH(i_op−1) is defined. If the measured SIR or MIfalls in the neighborhood, the curve cv(i_op) corresponding to the idealthreshold TH(i_op−1) can be well tracked; and the pair of the measuredSIR (or MI) and the measured BLER will effectively indicate a point onthe curve cv(i_op−1). If the measured BLER is higher than the targetvalue target_BLER like the scenario shown in FIG. 4, it is implied thatthe current threshold TH(i_op−1) is less than the ideal thresholdTH(i_op−1); so the current threshold TH(i_op−1) is adjusted byincreasing its value. On the contrary, if the measured BLER is lowerthan the target value target_BLER, the current threshold TH(i_op−1) istoo high and it is adjusted by lowering its value.

Following the discussion of FIG. 4, please refer to FIG. 5 illustratinga flow 100 for adjust the thresholds according to an embodiment of theinvention. The flow 100 includes the following steps.

Step 102: While a measured SIR (or MI) is obtained, the flow 100 canstart. First, quantize (categorize) the currently adopted communicationparameter combination, e.g., TFRC, by finding which combination schemethe currently adopted communication parameter combination belongs to.The found combination scheme is identified as the operating combinationscheme MCS(i_op). Corresponding to the operating combination schemeMCS(i_op), adjustment for the current bottom threshold TH(i_op−1) (as anoperating bottom threshold) is considered.

Step 104: if the measured SIR or MI is in the neighborhood of thecurrent threshold TH(i_op−1), go to step 106; otherwise go to step 114.

Step 106: update measured BLER for the operating combination schemeMCS(i_op). In an embodiment, when the terminal 14 works under a givencombination scheme MCS(i), the estimation unit 24 of FIG. 1 can measurea short-term BLER by CRC information for the combination scheme MCS(i),and then collect and accumulate a long-term measured BLER(i) for thecombination scheme MCS(i) according to short-term measured BLER of thecombination scheme MCS(i). As the terminal 14 works with differentcombination schemes MCS(i1), MCS(i2), . . . etc over time, it collectscorresponding long-term measured BLER(i1), BLER(i2), . . . etc. When theterminal 14 again works with the combination scheme MCS(i1) and obtainsa new short-term measured BLER, the long-term measured BLER(i1) of thecombination scheme MCS(i1) is updated. In another embodiment, themeasured BLER used in step 106 is a short-term measurement.

Step 108: if the measured BLER is lower than the target valuetarget_BLER, go to step 110; otherwise go to step 112.

Step 110: update the current threshold TH(i_op−1) by lowering its value.For example, the current threshold TH(i_op−1) can be lowered by apredetermined decrement. Then the flow 100 can proceed to step 114.

Step 112: update the current threshold TH(i_op−1) by increasing itsvalue. For example, the current threshold TH(i_op−1) can be increased bya predetermined increment. Then the flow 100 can proceed to step 114.The increment can be equal to or different from the decrement of step110. The increment and/or the decrement can be constant, or can bedynamically set.

Step 114: finish the flow 100.

The flow 100 can be regularly or periodically executed based on eithershort or long intervals, and/or it can be executed whenever necessary.For the first execution, the flow 100 can start with the thresholds setto predetermined initial values (e.g., thresholds designed for channelof predetermined characteristics, such as thresholds for a staticchannel) as initial guess. As the terminal 14 communicates withdifferent combination schemes at different times, different thresholdsrespectively corresponding to the adopted combination schemes can berespectively adjusted toward their ideal values which adapt actualchannel characteristics. Because the flow 100 works with a target valueof BLER, it implements a target BLER criterion for threshold adjustment.

Please refer to FIG. 6 illustrating another threshold decisioncriterion. For a given communication parameter combination and a givenchannel characteristics, throughput increases as SIR (or MI) increases.This correlative relation is illustrated by curves tp(i−1), tp(i) andtp(i+1) respectively corresponding to combinations schemes MCS(i−1),MCS(i) and MCS(i+1). The curves tp(i−1), tp(i) and tp(i+1) respectivelyhave maximum throughputs TPmax(i−1), TPmax(i) and TPmax(i+1), as well asa minimum throughput TPmin. The maximum throughput TPmax(i) is achievedwhen BLER is 0, i.e., a perfect transmission without any error; on theother hand, the minimum throughput TPmin corresponds to BLER of 0, i.e.,transmitted data are all incorrect. The combination scheme MSC(i+1)corresponds to a higher CQI, so it has a higher maximum throughputTPmax(i+1). However, the higher maximum throughput TPmax(i+1) demandshigher SIR or MI. Therefore, intersections of the curves tp(i−1), tp(i)and tp(i+1) can be utilized to indicate ideal thresholds: intersectionof the curves tp(i) and tp(i+1) defines an ideal value for the thresholdTH(i), and the intersection of the curves tp(i−1) and tp(i) defines anideal value for the threshold TH(i−1). With SIR (or MI) lower than thethreshold TH(i), throughput by communication adopting the combinationscheme MCS(i+1) becomes lower than that of the combination schemeMCS(i), so the CQI corresponding to the combination scheme MCS(i+1) isnot preferred; instead, the mapping function defined between thethresholds TH(i−1) and TH(i) is used for proper SIR (or MI) to CQImapping.

For a inside understanding, notice that a long-term overall throughputof correct data, T(TH(0), TH(1), . . . , TH(i), . . . , TH(N−1)), can beexpressed as:

${T\left( {{{TH}(0)},{{TH}(1)},\cdots,{{TH}\left( {N - 1} \right)}} \right)} = {\sum\limits_{i = 0}^{N}\; {{R(i)} \cdot {\int_{{TH}{({i - 1})}}^{{TH}{(i)}}{{\left\lbrack {1 - {e\left( {i,z} \right)}} \right\rbrack \cdot {f(z)}}\ {z}}}}}$

where −∞=TH(−1)=TH(0)=−∞≦TH(1)≦TH(2)≦ . . . ≦TH(N−1)≦TH(N)=∞, R(i) is anominal throughput (e.g., throughput regardless whether data are corrector not) corresponding to the combination scheme MCS(i), and e(i,z) is anerror rate (e.g., BLER) corresponding to the combination scheme MCS(i)under SIR (or MI) of value z. Along with R(i) and (1−e(i,z)), throughputof correct data while communicating by the combination scheme MCS(i) isobtained by integration over SIR (or MI) valued from the thresholdsTH(i−1) to TH(i). To optimize the overall throughput T(TH(0), TH(N−1)),the optimization condition R(i)*[1−e(i, TH(i))]=R(i+1)*[1−e(i+1, TH(i))]has to be satisfied for i=1 to (N−1). That is, throughput of correctdata during the combination scheme MCS(i) under SIR (or MI) of valueTH(i) must equal that during the combination scheme MCS(i+1) under SIR(or MI) of value TH(i) to fulfill the optimization condition. Sincethreshold decision of FIG. 6 sets ideal value of the threshold TH(i) tothe SIR (or MI) value corresponding to the intersection of the curvestp(i) and tp(i+1), the optimization condition can be satisfied.

Different channel characteristics lead to different curve tp(i) anddifferent threshold TH(i−1). To approach the ideal threshold TH(i−1) atintersection of the curves tp(i−1) and tp(i) as well as the idealthreshold TH(i) at intersection of the curves tp(i) and tp(i+1),measured SIR (or MI), measured BLER and measured throughput of thecombination schemes MCS(i−1), MCS(i) and MCS(i+1) are referred to followactual behavior of the curves tp(i−1), tp(i) and tp(i+1). To implementthe adjustment, the estimation unit 24 (FIG. 1) collects measuredBLER(i) and measured throughput U(i) (of long-term or short-term) fordifferent scheme combination MSC(i).

Following discussion of FIG. 6, please refer to FIG. 7 and FIG. 8respectively illustrating threshold updating according to embodiments ofthe invention. As shown in FIG. 7, when the terminal 14 communicateswith a given operating combination scheme MCS(i_op) and a measured SIR(or MI) is obtained, if the measured SIR (or MI) fall into aneighborhood around the current threshold TH(i_op−1), measuredthroughput U(i_op) of the operating combination scheme MCS(i_op) can beupdated, and adjustment of the threshold TH(i_op−1) can be considered;if the measured BLER(i_op) is neither close to 0 nor close to 1, thecurrent threshold TH(i_op−1) can be updated by increasing its value ifthe measured throughput U(i_op) of the operating combination schemeMCS(i_op) is lower than the measured throughput U(i_op−1) correspondingto the combination scheme MCS(i_op−1), like the scenario shown in FIG.7. On the contrary, if the measured throughput U(i_op) is higher thanthe measured throughput U(i_op−1), the current threshold TH(i_op−1) ishigher than the ideal threshold TH(i_op−1), so the current thresholdTH(i_op−1) is adjusted by lowering its value.

On the other hand, if the measured BLER(i_op) is close to 1, i.e., fallsin a predetermined proximity of the upper bound of BLER, the currentthreshold TH(i_op−1) is too small; the current threshold TH(i_op−1)intersects the curve tp(i_op) or tp(i_op−1) at minimum throughput TPmin.Then the current value of the threshold TH(i_op−1) can be adjusted byincreasing. If the measured BLER(i_op) is close to 0, a lower bound ofBLER, the adjustment can proceed following the target BLER criterion.Notice when BLER(i_op) is 0, the optimization condition becomesR(i_op−1)=R(i_op)*[1−e(i_op, TH(i_op−1))]; or equivalently, e(i_op,TH(i_op−1))=1−R(i_op−1)/R(i_op). That is, the optimization conditionsuggests a target BLER of value (1−R(i_op−1)/R(i_op)) for adjusting thethreshold TH(i_op−1) with the target BLER criterion.

Since the threshold TH(i_op) can be considered as an upper threshold ofthe operating combination scheme MCS(i_op), adjustment for the thresholdTH(i_op) can be considered if the measured SIR (or MI) fall into aneighborhood around the current threshold TH(i_op), as shown in FIG. 8.If the measured BLER(i_op) is neither close to 0 nor close to 1, thecurrent threshold TH(i_op) can be updated by lowering its value if themeasured throughput U(i_op) of the operating combination schemeMCS(i_op) is lower than the measured throughput U(i_op+1) correspondingto the combination scheme MCS(i_op+1), like the scenario shown in FIG.8. On the contrary, if the measured throughput U(i_op) is higher thanthe measured throughput U(i_op+1), the current threshold TH(i_op−1) islower than the ideal threshold TH(i_op−1), so the current thresholdTH(i_op−1) is adjusted by increasing its value.

Following the discussion of FIG. 7 and FIG. 8, please refer to FIG. 9illustrating a flow 200 for adjust the thresholds according to anembodiment of the invention. The flow 200 includes the following steps.

Step 202: While a measured SIR (or MI) is obtained, the flow 200 starts.First, quantize (categorize) the currently adopted communicationparameter combination, e.g., TFRC, by finding which combination schemethe currently adopted communication parameter combination belongs to.The found combination scheme is identified as the operating combinationscheme MCS(i_op). Corresponding to the operating combination schemeMCS(i_op), adjustment for the current bottom threshold TH(i_op−1) (as anoperating bottom threshold) and the top threshold TH(i_op) can beconsidered in the following steps.

Step 204: if the measured SIR (or MI) is in the neighborhood of thecurrent threshold TH(i_op−1), go to step 206; otherwise go to step 218.

Step 206: update the measured throughput U(i_op) for the operatingcombination scheme MCS(i_op). In an embodiment, when the terminal 14works under a given combination scheme MCS(i), the estimation unit 24 ofFIG. 1 can measure a short-term throughput for the combination schemeMCS(i), and then collect and accumulate a long-term throughput U(i) forthe combination scheme MCS(i) according to the short-term measuredthroughput of the combination scheme MCS(i). As the terminal 14 workswith different combination schemes MCS(i1), MCS(i2), . . . etc, itcollects corresponding long-term throughput U(i1), U(i2), . . . etc.When the terminal 14 again works the combination scheme MCS(i1) andobtains a new short term measured throughput, the long term measuredthroughput U(i1) of the combination scheme MCS(i1) is updated. Inanother embodiment, the measured throughput used in step 206 is ashort-term measurement.

Step 208: if the measured BLER(i_op−1) is close to 0 or 1, go to step216, otherwise proceed to step 210.

Step 210: if the measured throughput U(i_op) is higher than the measuredthroughput U(i_op−1), proceed to step 212, otherwise proceed to step214.

Step 212: lower the threshold TH(i_op−1) for adjustment and then proceedto step 234. For example, the threshold TH(i_op−1) can be decreased bysubtracting a decrement from its current value.

Step 214: increase the threshold TH(i_op−1) and the proceed to step 234.For example, the threshold TH(i_op−1) can be increased by adding aincrement to its current value.

Step 216: execute an exception processing. The detail will be discussedin FIG. 10.

Step 218: if the measured SIR (or MI) is in the neighborhood of thethreshold TH(i_op), go to step 220; otherwise go to step 234. Noticethat the range covered by the neighborhood of the threshold TH(i_op)does not have to overlap that of the threshold TH(i_op−1).

Step 220: update the measured throughput U(i_op) for the operatingcombination scheme MCS(i_op).

Step 222: if the measured BLER(i_op) is close to 0, proceed to step 234,otherwise proceed to step 224.

Step 224: if the measured BLER(i_op) is close to 1, proceed to step 232,otherwise proceed to step 226.

Step 226: if the measured throughput U(i_op) is higher than the measuredthroughput U(i_op+1), proceed to step 228, otherwise proceed to step230.

Step 228: increase the threshold TH(i_op), then proceed to step 234.

Step 230: decrease the threshold TH(i_op), then proceed to step 234.

Step 232: execute an exception procedure which will be discussed withFIG. 10.

Step 234: finish the flow 200.

Please refer to FIG. 10 illustrating the exception processing of thestep 216, which includes the following steps.

Step 300: if the measured BLER(i_op−1) is close to 0, proceed to step302, otherwise go to step 304.

Step 302: follow the target BLER criterion of FIG. 5 for adjustment ofthe threshold TH(i_op−1), i.e., update the operating bottom thresholdTH(i_op−1) according to a comparison between a target value (targetBLER) and the measured BLER(i_op). As discussed above, the target BLERcan be set to (1−R(i_op−1)/R(i_op)).

Step 304: if the measured BLER(i_op−1) is close to 0, go to step 306;otherwise proceed to step 234.

Step 306: adjust the threshold TH(i_op−1) by increasing its value. Thevalue of the threshold TH(i_op−1) can be boosted by an increment largerthan that used in step 214 and/or step 228 of FIG. 9.

The exception procedure of step 232 (FIG. 9) is similar to step 306 ofFIG. 10; the threshold TH(i_op) can be boosted if the measuredBLER(i_op) is close to 1.

The flow 200 can be regularly or periodically executed based on eithershort or long intervals; and/or it can be executed whenever necessary.As the terminal 14 communicates with different combination schemes atdifferent times, different thresholds respectively corresponding to theadopted combination schemes can be respectively adjusted toward theirideal values. Because the flow 200 works based on maximizing throughput,it implements an optimum (maximum) throughput criterion for thresholdadjustment.

In addition to SIR, MI, MCS, BLER and/or throughput, effect/influence ofother base station information can also be considered during thresholdadaption and CQI reporting of the invention. For example, besidesupdating the threshold TH(.) according to the flows 100 or 200, theterminal 14 can further tune the threshold TH(.) according to powerscheduling information of the serving base station 12. During operationof the terminal 14, it keeps on collecting power scheduling informationwhich reflects how the serving base station 12 schedules power fordifferent levels CQI(.). By analyzing power scheduling information, Ifthe terminal 14 finds that the base station schedules additional powerfor a given indicator level CQI(i), then the terminal can update thecorresponding threshold TH(i) by lowering (decreasing) it. The thresholdTH(i) can be offset (decreased) by an amount which reflects theadditional transmission power of the base station known from the thirdmeasurement; e.g., the offset amount can be set greater if theadditional transmission power is greater.

For example, in embodiments where SIR is utilized to determine CQI, theSIR threshold TH(i) can be lowered by 2 dB if the base station 12schedules additional 2 dB transmission power for the corresponding levelCQI(i). That is, assuming that SIR is originally 1 dB lower than thethreshold TH(i) and thus fails to match the level CQI(i), the terminal14 can set CQI equal to level CQI(i) after the threshold TH(i) islowered by 2 dB, because the additional 2 dB transmission power canboost SIR by 2 dB to match the originally unachievable level CQI(i).Similarly, for other embodiments where MI is utilized to determine CQI,the terminal 14 can decrements the MI threshold TH(i) by a MI offsetamount associated with the additional transmission power scheduled bythe base station 12.

Please refer to FIG. 12 illustrating a flow 400 which integrates effectof base station information into threshold adaption and CQI reporting.The flow 400 includes steps 402, 404 and 406.

Step 402: use the flow 100 (FIG. 5) or the flow 200 (FIG. 9 and FIG. 10)to adapt the thresholds TH(.).

Step 404: further update any the threshold(s) TH(.) if power schedulinginformation reflects additional scheduled power for corresponding levelCQI(.).

Step 406: determine value of CQI according to measured SIR (or MI) andthe thresholds TH(.).

By updating threshold(s) TH(.) according to power schedulinginformation, flow 400 equivalently updates CQI according to powerscheduling information; that is, CQI can be changed from a lower levelto a higher level when power scheduling information reflects that thebase station 12 schedules additional transmission power for the higherlevel. Note that order of steps 402 and 404 can be exchanged.

For implementation of the threshold setting according to FIG. 3 and/orFIG. 6, the adaptation module 26 of FIG. 1 executes the flow 100 of FIG.5 and/or the flow 200 of FIG. 9; furthermore, the adaptation module 26can execute step 404 of FIG. 12. The adaptation module 26 can beimplemented by hardware, firmware and/or software. For example, theterminal 14 can include a memory (volatile or nonvolatile) which recordscodes, and a processor which executes the codes to implement the flow100 and/or 200.

To sum up, for adaptation of channel characteristics, the inventionprovides CQI reporting which dynamically updates SIR (or MI) to CQImapping relation by adjusting thresholds of the piecewise mappingfunctions. Comparing arts with constant thresholds which are vulnerableto variation of channel characteristics, the thresholds decision of theinvention not only tracks actual channel characteristics and additionalinformation of base station, but also achieves target BLER and/oroptimum throughput. Though some technique terms used in discussion aresimilar to those used in 3GPP standards/specifications, the inventioncan be generalize to communication systems which need channel qualityreporting for setting of communication parameters.

While the invention has been described in terms of what is presentlyconsidered to be the most practical and preferred embodiments, it is tobe understood that the invention needs not be limited to the disclosedembodiment. On the contrary, it is intended to cover variousmodifications and similar arrangements included within the spirit andscope of the appended claims which are to be accorded with the broadestinterpretation so as to encompass all such modifications and similarstructures.

What is claimed is:
 1. A method reporting a channel quality indicator ofa communication system, comprising: detecting a first measurementreflecting a first communication quality of the communication system;providing a number of first references which respectively correspond toa number of indicator levels; providing the channel quality indicatoraccording to the number of indicator levels and a relation between thefirst measurement and the number of first references; and updating atleast one of the number of first references according to a secondmeasurement which reflects a second communication quality of thecommunication system.
 2. The method as claimed in claim 1, whereinproviding the channel quality indicator includes: according to whetherthe first measurement is greater than a chosen one of the number offirst references, determining if the channel quality indicator is setequal to the indicator level corresponding to the chosen firstreference.
 3. The method as claimed in claim 1, wherein the firstmeasurement reflects a signal to interference ratio (SIR) of thecommunication system.
 4. The method as claimed in claim 1, wherein thefirst measurement reflects a mutual information between transmittedsignal and received signal of the communication system.
 5. The method asclaimed in claim 4 further comprising: evaluating the mutual informationof the communication system by mapping SIR through a SIR-to-MI mappingfunction.
 6. The method as claimed in claim 1, wherein the secondmeasurement reflects a bit error rate of the communication system. 7.The method as claimed in claim 1, wherein the second measurementreflects a throughput of the communication system.
 8. The method asclaimed in claim 1, wherein the communication system adopts one of aplurality of communication parameter combinations for communication, thecommunication parameter combinations are categorized to a plurality ofcombination schemes, each of the combination schemes corresponds to twoadjacent first references respectively representing a bottom thresholdand an upper threshold; and the method further comprising: identify anoperating combination scheme which the adopted communication parametercombination is categorized to; identify an operating bottom thresholdwhich is the bottom threshold corresponding to the operating combinationscheme; and if the first measurement falls in a predeterminedneighborhood of the operating bottom threshold, updating the firstreference which represents the operating bottom threshold.
 9. The methodas claimed in claim 8 further comprising: while updating the firstreference representing the operating bottom threshold, lowering orincreasing the first reference representing the operating bottomthreshold according to whether the second measurement is less than orgreater than a target value.
 10. The method as claimed in claim 1,wherein the communication system adopts one of a plurality ofcommunication parameter combinations for communication, each of thethresholds corresponds to at least one of the plurality of communicationparameter combinations, the communication parameter combinations arecategorized to a plurality of combination schemes, each of thecombination schemes corresponds to two adjacent first referencesrespectively representing a bottom threshold and an upper threshold; andthe method further comprising: collecting a plurality of the secondmeasurements, each of the second measurements corresponding to one ofthe combination schemes; collecting a plurality of auxiliarymeasurements, each of the auxiliary measurements reflecting an auxiliaryquality of the communication system and corresponding to one of thecombination schemes; identify an operating combination scheme which theadopted communication parameter combination is categorized to; identifyan operating bottom threshold and an operating upper threshold which arerespectively the bottom threshold and the upper threshold correspondingto the operating combination scheme; identify a lower operatingcombination scheme whose upper threshold is the operation bottomthreshold; and if the first measurement falls in a predeterminedneighborhood of the operating bottom threshold and if the auxiliarymeasurement corresponding to the lower combination scheme falls out oftwo predetermined ranges, updating the first reference representing theoperating bottom threshold.
 11. The method as claimed in claim 10further comprising: while updating the first reference representing theoperating bottom threshold, lowering or increasing the first referencerepresenting the operating bottom threshold according to whether thesecond measurement corresponding to the operating combination scheme isgreater than or less than that corresponding to the lower combinationscheme.
 12. The method as claimed in claim 10, wherein the twopredetermined ranges are respect proximities of a bottom bound and anupper bound of the auxiliary measurements, and the method furthercomprising: if the first measurement falls in the predeterminedneighborhood of the operating bottom threshold and if the auxiliarymeasurement corresponding to the lower operating combination schemefalls in the predetermined range of the upper bound, increasing thefirst reference representing the operating bottom threshold.
 13. Themethod as claimed in claim 12 further comprising: if the firstmeasurement falls in the predetermined neighborhood of the operatingbottom threshold and if the auxiliary measurement corresponding to thelower operating combination scheme falls in the predetermined range ofthe lower bound, updating the first reference representing the operatingbottom threshold according to a comparison between a target value andthe auxiliary measurement corresponding to the operating combinationscheme.
 14. The method as claimed in claim 10, further comprising: ifthe first measurement falls in a predetermined neighborhood of theoperating upper threshold and if the auxiliary measurement correspondingto the operating combination scheme falls out of the two predeterminedranges, updating the first reference representing the operating upperthreshold.
 15. The method as claimed in claim 14 further comprising:identifying a higher operating combination scheme whose bottom thresholdis the operating upper threshold; and while updating the first referencerepresenting the operating upper threshold, increasing or decreasing thefirst reference representing the operating upper threshold according towhether the second measurement corresponding to the operatingcombination scheme is greater than or less than that corresponding tothe higher operating combination scheme.
 16. The method as claimed inclaim 14, wherein the two predetermined ranges are respect proximitiesof a bottom bound and an upper bound of the auxiliary measurements, andthe method further comprising: if the first measurement falls in thepredetermined neighborhood of the operating upper threshold and if theauxiliary measurement corresponding to the operating combination schemefalls in the predetermined range of the upper bound, increasing theoperating upper threshold.
 17. The method as claimed in claim 10,wherein the first measurement reflects a signal to interference ratio ofthe communication system, each of the second measurements reflects athroughput of the communication system when one of the communicationparameter combinations is adopted, and each of the auxiliarymeasurements reflects a bit error rate of the communication system whenone of the communication parameter combinations is adopted.
 18. Themethod as claimed in claim 1 further comprising: updating at least oneof the number of first references according to a third measurement whichreflects an information of a base station of the communication system.19. The method as claimed in claim 18, wherein the third measurementreflects a power scheduling information of the base station.
 20. Themethod as claimed in claim 18, wherein updating the at least one of thenumber of first references according to the third measurement including:decreasing the at least one of the number of first reference if thethird measurement reflects that the base station schedules an additionaltransmission power for the indicator level which corresponds to thechosen first reference.
 21. A method reporting a channel qualityindicator of a communication system, comprising: detecting a firstmeasurement reflecting a first communication quality of thecommunication system; providing a number of first references whichrespectively correspond to a number of indicator levels; providing thechannel quality indicator according to the number of indicator levelsand a relation between the first measurement and the number of firstreferences; and updating one of the number of first references accordingto a second measurement and a third measurement which respectivelyreflect a second communication quality of the communication system andan information of a base station of the communication system.
 22. Themethod as claimed in claim 21, wherein the third measurement reflects apower scheduling information of the base station.
 23. The method asclaimed in claim 21, wherein updating one of the number of firstreferences according to the third measurement including: decreasing theone of the number of first references if the third measurement reflectsthat the base station schedules an additional transmission power for theindicator level which corresponds to the one of the number of firstreference.
 24. The method as claimed in claim 21, wherein the firstmeasurement reflects a signal to interference ratio (SIR) of thecommunication system.
 25. The method as claimed in claim 21, wherein thefirst measurement reflects a mutual information between transmittedsignal and received signal of the communication system.
 26. The methodas claimed in claim 21, wherein the second measurement reflects a biterror rate of the communication system.
 27. The method as claimed inclaim 21, wherein the second measurement reflects a throughput of thecommunication system.
 28. The method as claimed in claim 21, whereinupdating the one of the number of first references including: offsettingthe one of the number of first references by an amount which reflects anadditional transmission power of the base station known from the thirdmeasurement.
 29. A method reporting a channel quality indicator of acommunication system, comprising: obtaining a measurement; and updatingthe channel quality indicator according to the measurement, such thatthe channel quality indicator changes from a first indicator level to asecond indicator level when the measurement reflects that a base stationof the communication system schedules additional transmission power forthe second indicator level.
 30. The method as claimed in claim 29,wherein the second indicator level is higher than the first indicatorlevel.
 31. The method as claimed in claim 29, wherein the measurementreflects a power scheduling information of the base station.
 32. Anapparatus reporting a channel quality indicator of a communicationsystem, comprising: an estimation unit for providing a measurement; anda module for updating the channel quality indicator according to themeasurement, such that the channel quality indicator changes from afirst indicator level to a second indicator level when the measurementreflects that a base station of the communication system schedulesadditional transmission power for the second indicator level.
 33. Theapparatus as claimed in claim 32, wherein the second indicator level ishigher than the first indicator level.
 34. The apparatus as claimed inclaim 32, wherein the measurement reflects a power schedulinginformation of the base station.